Chapter 7 · Let us assessTextbook pages 151–152

Let Us Assess & Extended Activities – Solutions വിലയിരുത്താം

All fifteen end-of-chapter questions with model answers. Do the chloride test in a virtual test tube, push a glowing splinter into oxygen, follow chlorine through two wash bottles, bleach a moist and a dry cloth, hear hydrogen “pop”, connect a battery to diamond and to graphite and turn lime water milky. Q2 and Q14 are tap-to-sort, and Q8 is a balanced argument. Try each question yourself first, then open the answer. After that come the three extended activities തുടർപ്രവർത്തനങ്ങൾ: a model note on chlorine bleaching, a printable table of uses and a report template for a fertiliser-factory visit.

📖 What you need (pages 3–9 of this guide)

Hydrogen: Zn + dilute HCl; burns with a “pop” പോപ്പ് ശബ്ദം; isotopes ഐസോടോപ്പുകൾ; fuel and calorific value കലോറിക മൂല്യം (page 3, page 4).
Allotropes of carbon രൂപാന്തരങ്ങൾ: diamond, graphite, graphene, fullerene; amorphous forms (page 5). CO₂ and the lime-water test (page 6).
Nitrogen and fertilisers ജൈവവളം · രാസവളം (page 7); oxygen from KMnO₄, ozone and CFCs (page 8).
Chlorine: preparation, bleaching ബ്ലീച്ചിങ് പൗഡർ by nascent oxygen നവജാത ഓക്സിജൻ, chloride test (page 9).

Parts marked go further are beyond the textbook. The experiments with KMnO₄ + concentrated HCl, heating KMnO₄ and burning hydrogen are shown here as virtual teacher demonstrations only.

Question 1 · Pick the gas

1. ചില വാതകങ്ങൾ ബോക്സിൽ നൽകിയിരിക്കുന്നു. ചുവടെ കൊടുത്തിരിക്കുന്ന ചോദ്യങ്ങൾക്ക് യോജിച്ചവ കണ്ടെത്തി എഴുതുക. Some gases are given in the box. Find the right one for each question below.

hydrogen, chlorine, oxygen, nitrogen

KMnO₄ ന്റെ താപീയ വിഘടനഫലമായി ഉണ്ടാകുന്ന വാതകം. The gas formed when KMnO₄ decomposes on heating.
ജലശുദ്ധീകരണത്തിന് ഉപയോഗിക്കുന്ന വാതകം. The gas used to purify water.
സസ്യങ്ങളുടെ വളർച്ചയ്ക്ക് അനിവാര്യമായ മൂലകം. The element essential for the growth of plants.
ജ്വലനസ്വഭാവം ഉള്ളതും ജലത്തിന്റെ വൈദ്യുതവിശ്ലേഷണത്തിലൂടെ ലഭിക്കുന്നതുമായ വാതകം. The gas that burns and is obtained by the electrolysis of water.

👆 Tap a gas for each part

a) from heating KMnO₄

b) used to purify water

c) essential for plant growth

d) burns · from electrolysis of water

a) Oxygen ഓക്സിജൻ – 2KMnO₄ → K₂MnO₄ + MnO₂ + O₂
b) Chlorine ക്ലോറിൻ – a disinfectant അണുനാശിനി
c) Nitrogen നൈട്രജൻ
d) Hydrogen ഹൈഡ്രജൻ – it burns (with a pop) and is got industrially by the electrolysis of water ജലത്തിന്റെ വൈദ്യുതവിശ്ലേഷണം. (Oxygen also forms in electrolysis, but oxygen does not burn; it only helps burning.)

Question 2 · Crystalline or amorphous?

2. കാർബണിന്റെ വിവിധ രൂപാന്തരങ്ങൾക്ക് ഉദാഹരണങ്ങൾ കണ്ടെത്തി പട്ടിക പൂർത്തിയാക്കുക. Find examples of the different allotropes of carbon and complete the table (crystalline allotropes ക്രിസ്റ്റലീയ രൂപാന്തരങ്ങൾ · amorphous allotropes അമോർഫസ് രൂപാന്തരങ്ങൾ).

👆 Tap the group for each form of carbon – the table fills itself

Diamond വജ്രം

Charcoal ചാർക്കോൾ

Graphite ഗ്രാഫൈറ്റ്

Coke കോക്ക്

Graphene ഗ്രഫീൻ

Lamp black വിളക്കുകരി

Fullerene ഫുള്ളറീൻ

Coal കൽക്കരി

Crystalline allotropesക്രിസ്റ്റലീയ രൂപാന്തരങ്ങൾ	Amorphous allotropesഅമോർഫസ് രൂപാന്തരങ്ങൾ

Crystalline	Amorphous
diamond, graphite, graphene, fullerene	charcoal, coke, lamp black, coal

Allotropes രൂപാന്തരങ്ങൾ are different forms of the same element with different physical properties (Fig 7.3).

Question 3 · The chloride test

3. ക്ലോറൈഡ് ലവണത്തെ തിരിച്ചറിയാനുള്ള പരീക്ഷണം നൽകിയിരിക്കുന്നു. നിരീക്ഷണവും നിഗമനവും രേഖപ്പെടുത്തുക. The test to identify a chloride salt is given. Record the observation and the inference.

Experiment പരീക്ഷണം	Observation നിരീക്ഷണം	Inference നിഗമനം
i. Add AgNO₃ solution to a solution of the given salt.
ii. Add NH₄OH solution to the precipitate formed.

🧪 Do the test – the table above fills in as you go

Experiment	Observation	Inference
i. AgNO₃ solution added	A curdy white precipitate forms	The salt may be a chloride (silver chloride, AgCl, has formed)
ii. NH₄OH added to the precipitate	The precipitate dissolves	The precipitate is AgCl, so the salt is a chloride

For sodium chloride: NaCl + AgNO₃ → AgCl↓ + NaNO₃.

Question 4 · The best gas for the job

4. ചുവടെ കൊടുത്തിരിക്കുന്ന ഓരോ സന്ദർഭത്തിനും ഏറ്റവും അനുയോജ്യമായ വാതകം കണ്ടെത്തി എഴുതുക. (ക്ലോറിൻ, നൈട്രജൻ, സി.എഫ്.സി, ഓക്സിജൻ) Find the most suitable gas for each situation below. (chlorine, nitrogen, CFC, oxygen)

റോക്കറ്റ് ഇന്ധനങ്ങളിൽ ഓക്സീകാരിയായി As the oxidiser in rocket fuels
ഓസോൺ ശോഷണം Ozone depletion
വാഹനങ്ങളുടെ ടയറുകളിൽ നിറയ്ക്കുന്നതിന് For filling vehicle tyres

👆 Tap a gas for each situation (one gas is left over)

🚀 Oxidiser in rocket fuels

🌍 Ozone depletion

🚗 Filling vehicle tyres

• Oxidiser in rocket fuels – oxygen
• Ozone depletion ഓസോൺ പാളിയുടെ ശോഷണം – CFC ക്ലോറോഫ്ലൂറോകാർബണുകൾ (CFC)
• Filling vehicle tyres – nitrogen
(Chlorine is not needed here. It is the chlorine released from CFCs that attacks ozone, but the substance named for ozone depletion is CFC.)

Question 5 · Heating potassium permanganate

5. ഒരു ബോയിലിങ് ട്യൂബിൽ പൊട്ടാസ്യം പെർമാംഗനേറ്റ് ചൂടാക്കുന്നു. Potassium permanganate is heated in a boiling tube.

ബോയിലിങ് ട്യൂബിന്റെ ഉള്ളിലേക്ക് എരിയുന്ന തീപ്പെട്ടിക്കൊള്ളി കടത്തുക. നിരീക്ഷണം എന്ത്? A burning matchstick is put into the boiling tube. What is observed?
ഉണ്ടായ വാതകം ഏത്? Which gas is formed?

🔥 Virtual teacher demo – then test the gas

⚠ Heating KMnO₄ is a teacher-only experiment: the tube gets very hot and the crystals can spit. Watch it here.

a) The matchstick burns more brightly (with a bigger, brighter flame). A glowing splinter would burst into flame.
b) Oxygen, which supports combustion ജ്വലനസഹായി: 2KMnO₄ →(heat) K₂MnO₄ + MnO₂ + O₂

Question 6 · Making chlorine in the lab

6. ക്ലോറിൻ വാതകം ലാബിൽ നിർമ്മിക്കുന്നതുമായി ബന്ധപ്പെട്ട് ചുവടെ നൽകിയിരിക്കുന്ന ചോദ്യങ്ങൾക്ക് ഉത്തരമെഴുതുക. Answer these questions on preparing chlorine in the lab.

ക്ലോറിൻ വാതകം നിർമ്മിക്കാൻ ആവശ്യമായ രാസവസ്തുക്കൾ ഏതെല്ലാം? Which chemicals are needed to make chlorine?
ക്ലോറിൻ വാതകം ജലത്തിലൂടെ കടത്തിവിട്ട് ശേഖരിക്കുന്നു. കാരണം എന്ത്? Chlorine is passed through water before it is collected. Why?
ക്ലോറിൻ വാതകം ഗാഢ സൾഫ്യൂരിക് ആസിഡിലൂടെ കടത്തിവിടുന്നു. കാരണം എന്ത്? Chlorine is passed through concentrated sulphuric acid. Why?

🎬 Step by step – follow the gas through the wash bottles (virtual teacher demo)

⚠ Chlorine is a poisonous gas. This preparation is done only by a teacher, in a fume cupboard. Concentrated HCl and concentrated H₂SO₄ burn the skin. Never try it at home.

a) Potassium permanganate (KMnO₄) and concentrated hydrochloric acid (HCl) (gently heated):
2KMnO₄ + 16HCl → 2KCl + 2MnCl₂ + 8H₂O + 5Cl₂
b) To remove the hydrogen chloride (HCl) vapour that comes along with the chlorine. HCl dissolves readily in water.
c) To remove water vapour (to dry the chlorine). Concentrated sulphuric acid absorbs moisture.
The dry chlorine is collected by upward displacement of air because it is denser than air.

Question 7 · Why moisture for bleaching?

7. ക്ലോറിന്റെ ബ്ലീച്ചിങ്ങിന് ഈർപ്പം ആവശ്യമാണ്. കാരണം വ്യക്തമാക്കുക. Moisture is needed for bleaching by chlorine. Explain the reason.

🧺 Dry cloth vs moist cloth in chlorine

Chlorine bleaches by oxidation with nascent oxygen നവജാത ഓക്സിജൻ, and this oxygen forms only when chlorine reacts with water:
H₂O + Cl₂ → HCl + HOCl (hypochlorous acid ഹൈപ്പോക്ലോറസ് ആസിഡ്)
HOCl → HCl + [O]
The nascent oxygen [O] oxidises the coloured substance to a colourless one. Dry chlorine cannot form HOCl, so it cannot bleach: a dry cloth keeps its colour, a moist cloth loses it.

Question 8 · Give up chemical fertilisers completely?

8. “രാസവളം പൂർണമായി ഉപേക്ഷിച്ച് ജൈവവള പ്രയോഗം പ്രോത്സാഹിപ്പിക്കണം” എന്ന വാദഗതിയോട് നിങ്ങളുടെ അഭിപ്രായമെന്ത്? ഉത്തരം സാധൂകരിക്കുക. What is your opinion on the argument “Chemical fertilisers should be given up completely and the use of organic manure should be encouraged”? Justify your answer.

An opinion question has no single “right” side. Marks come from reasons on both sides (Table 7.4) and a clear conclusion that follows from them.

⚖️ Weigh the points – which side does each one support?

Organic manure ജൈവവളം adds humus and improves the soil.

Organic manure has only a small amount of nutrients; very large quantities are needed.

Organic manure helps earthworms and useful soil microbes.

Chemical fertilisers രാസവളം supply nutrients in known amounts and act quickly.

Too much chemical fertiliser can harm the soil and pollute water.

Stopping chemical fertilisers completely may lower crop yields.

Organic manure can be made from farm and kitchen waste.

Organic manure is bulky and releases nutrients slowly.

My opinion: I agree that organic manure should be encouraged, but I do not agree that chemical fertilisers should be given up completely.
Points for the slogan: organic manure adds humus, improves soil texture and water-holding, helps earthworms and soil microbes, recycles farm waste and causes little pollution. Too much chemical fertiliser can spoil the soil and pollute water bodies.
Points against it: organic manure has a low nutrient content and is bulky, so very large amounts are needed, and it acts slowly. Chemical fertilisers supply measured amounts of nutrients quickly; dropping them all at once could lower crop yields and food production.
Conclusion: both have merits and limitations (Table 7.4). The best path is scientific, balanced use: plenty of organic manure for soil health, plus chemical fertilisers only in the amount the crop needs (for example after a soil test). go further Agricultural scientists call this integrated nutrient management.
Other opinions can also earn full marks if they give reasons on both sides and a conclusion that follows from them.

Question 9 · Making and testing hydrogen

പരീക്ഷണശാലയിൽ ഹൈഡ്രജൻ വാതകം നിർമ്മിക്കാൻ ആവശ്യമായ രാസവസ്തുക്കൾ ഏതെല്ലാം? Which chemicals are needed to make hydrogen in the laboratory?
ഉണ്ടായ വാതകം ഹൈഡ്രജൻ ആണെന്ന് എങ്ങനെ മനസിലാക്കാം? How can we tell that the gas formed is hydrogen?

💥 The pop test

⚠ Hydrogen mixed with air burns explosively. Only a very small amount, in a teacher demonstration, and no flame near any hydrogen source.

a) Zinc (granules) and dilute hydrochloric acid: Zn + 2HCl → ZnCl₂ + H₂↑
b) Bring a burning splinter to the mouth of the tube: the gas burns with a “pop” sound പോപ്പ് ശബ്ദം. That shows it is hydrogen. (A glowing splinter is the test for oxygen, not hydrogen.)

Question 10 · Hydrogen as a fuel, and its isotopes

10.

ഹൈഡ്രജൻ ഒരു ഇന്ധനമായി ഉപയോഗിച്ചാൽ ഉണ്ടാകുന്ന മേന്മകൾ എന്തെല്ലാം? What are the merits of using hydrogen as a fuel?
ഹൈഡ്രജന്റെ ഐസോടോപ്പുകൾ ഏതെല്ലാം? What are the isotopes of hydrogen?
ഇവയിൽ ന്യൂട്രോൺ ഇല്ലാത്ത ഐസോടോപ്പ് ഏത്? Which of them has no neutron?

⚛️ Three isotopes of hydrogen – tap one

a) • Very high calorific value കലോറിക മൂല്യം (143 kJ/g, the highest in Fig 7.2).
• On burning it forms only water (2H₂ + O₂ → 2H₂O), so it causes little pollution – no smoke, no CO₂.
b) Protium, deuterium and tritium.
c) Protium (1 proton, 1 electron, 0 neutrons; mass number 1).

Question 11 · Calorific value

11.

കലോറിക മൂല്യം എന്നാൽ എന്ത്? What is calorific value?
ചില ഇന്ധനങ്ങൾ ബോക്സിൽ നൽകിയിരിക്കുന്നു. ഇവയിൽ കലോറിക മൂല്യം ഏറ്റവും കൂടിയ ഇന്ധനം ഏത്? Some fuels are given in the box. Which has the highest calorific value?
petrol, coal, ethanol, hydrogen, methanol
ഹൈഡ്രജൻ ഗാർഹിക ഇന്ധനമായി ഉപയോഗിക്കുന്നില്ല. ഈ പരിമിതിക്ക് കാരണങ്ങൾ എന്തെല്ലാം? Hydrogen is not used as a household fuel. What are the reasons for this limitation?

📊 The five fuels of the box (values from Fig 7.2)

a) Calorific value കലോറിക മൂല്യം is the heat energy released when a unit mass (1 g) of a fuel burns completely. It is given in kJ/g.
b) Hydrogen (143 kJ/g; petrol 48, coal 33, ethanol 30, methanol 23).
c) • Hydrogen burns explosively, so it is dangerous in homes.
• It is difficult to store and transport (it is a very light gas that is hard to keep in a container).

Questions 12 & 13 · Diamond and graphite with a battery

12. ക്രിസ്റ്റൽ ഘടനയുള്ള കാർബണിന്റെ ഒരു രൂപാന്തരമാണ് വജ്രം. വജ്രം വൈദ്യുതിയെ കടത്തിവിടുന്നില്ല. കാരണം എന്ത്? Diamond is a crystalline allotrope of carbon. Diamond does not conduct electricity. Why?

13.

കാർബണിന്റെ വൈദ്യുത ചാലകമായ രൂപാന്തരമേത്? Which allotrope of carbon conducts electricity?
ഇതിനു കാരണം വ്യക്തമാക്കുക. Explain the reason.
ഈ രൂപാന്തരത്തിന്റെ രണ്ട് ഉപയോഗങ്ങൾ എഴുതുക. Write two uses of this allotrope.

🔋 Connect a battery and a bulb to each crystal

A flat, simplified picture: real diamond is a 3-D network, and the bonds are drawn only to show how many each atom has.

In diamond വജ്രം each carbon atom uses all four of its outer electrons (valency 4) to form covalent bonds with four other carbon atoms. No free electrons are left to move through the crystal and carry current, so diamond does not conduct electricity.

a) Graphite ഗ്രാഫൈറ്റ്.
b) In graphite each carbon atom is bonded to only three other carbon atoms in flat hexagonal layers. The fourth electron of each atom is free and can move along the layers, so graphite conducts electricity വൈദ്യുതചാലകത.
c) Any two: electrodes in dry cells (it conducts electricity); pencil lead (soft, leaves a mark on paper); lubricant സ്നേഹകം (layers slide over each other). The question is about a conductor, so make sure one of your two uses is the dry-cell electrode.

Question 14 · Match the allotrope to its use

14. ചേരുംപടി ചേർത്ത് എഴുതുക. Match column A with column B.

A	B
Diamond വജ്രം	Nanotechnology നാനോടെക്നോളജി
Graphite ഗ്രാഫൈറ്റ്	Making jewellery ആഭരണ നിർമ്മാണം
Graphene ഗ്രഫീൻ	Lubricant സ്നേഹകം

👆 Tap the use that matches each allotrope

💎 Diamond

✏️ Graphite

🕸️ Graphene

Diamond – making jewellery · Graphite – lubricant · Graphene – nanotechnology നാനോടെക്നോളജി

Question 15 · Calcium carbonate and dilute HCl

15.

ഒരു ടെസ്റ്റ് ട്യൂബിൽ നേർപ്പിച്ച ഹൈഡ്രോക്ലോറിക് ആസിഡും കാൽസ്യം കാർബണേറ്റും എടുത്തിരിക്കുന്നു. ഉണ്ടായ വാതകം ഏത്? Dilute hydrochloric acid and calcium carbonate are taken in a test tube. Which gas is formed?
രാസപ്രവർത്തനത്തിന്റെ സമവാക്യം പൂർത്തിയാക്കുക. Complete the equation: CaCO₃ + 2HCl → CaCl₂ + ____ + ____
ഉണ്ടായ വാതകം തെളിഞ്ഞ ചുണ്ണാമ്പുവെള്ളത്തിലൂടെ കടത്തി വിടുന്നു. നിരീക്ഷണം രേഖപ്പെടുത്തുക. The gas is passed through clear lime water. Record the observation.

🫧 Pass the gas into lime water ചുണ്ണാമ്പുവെള്ളം

CaCO₃ + 2HCl → CaCl₂ + + Choose the two missing products.

a) Carbon dioxide (CO₂).
b) CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂
c) The clear lime water turns milky go further (insoluble calcium carbonate forms: Ca(OH)₂ + CO₂ → CaCO₃ + H₂O).

⚠️ Four traps in these questions

Hydrogen: burning splinter → “pop”. Oxygen: glowing splinter → bursts into flame (Q5, Q9).
Dry chlorine does not bleach; it needs water to form HOCl and nascent oxygen (Q7).
Diamond does not conduct (no free electrons); graphite does (one free electron per carbon) (Q12, Q13).
Water removes HCl; concentrated H₂SO₄ removes water vapour – do not swap them (Q6).

Extended activities തുടർപ്രവർത്തനങ്ങൾ

Extended activity 1 · A note on the chemistry of chlorine bleaching

1. ക്ലോറിന്റെ ബ്ലീച്ചിങ് രസതന്ത്രത്തെക്കുറിച്ച് കുറിപ്പ് തയ്യാറാക്കി അവതരിപ്പിക്കുക. Prepare and present a note on the chemistry of bleaching by chlorine.

🎬 Step by step – from chlorine to a white cloth

The chemistry of bleaching by chlorine
Chlorine is a greenish-yellow gas with a pungent smell. It is used to bleach cotton, paper and pulp, and to make bleaching powder ബ്ലീച്ചിങ് പൗഡർ.
Observation. A dry coloured cloth kept in dry chlorine does not lose its colour. A moist coloured cloth in chlorine loses its colour. So moisture is needed.
Explanation. Chlorine reacts with water to form hydrochloric acid and hypochlorous acid ഹൈപ്പോക്ലോറസ് ആസിഡ്:
  H₂O + Cl₂ → HCl + HOCl
Hypochlorous acid is unstable and gives nascent oxygen നവജാത ഓക്സിജൻ [O], oxygen in the atomic state, which is very reactive:
  HOCl → HCl + [O]
The nascent oxygen oxidises the coloured substance into a colourless substance:
  coloured substance + [O] → colourless substance
So chlorine bleaches by oxidation, and only in the presence of water.
Bleaching powder. Dry chlorine passed over dry slaked lime gives bleaching powder, Ca(OCl)₂ (it smells of chlorine):
  2Ca(OH)₂ + 2Cl₂ → Ca(OCl)₂ + CaCl₂ + 2H₂O
Uses. Bleaching cloth and paper; disinfecting അണുനാശിനി drinking water and wells; making antiseptics and pesticides കീടനാശിനി.
Safety. Chlorine is poisonous: even a little irritates the nose, throat and lungs. Bleaching powder and bleach must be kept closed, away from children, and never mixed with acids or other cleaners.

✔ equations✔ nascent oxygen✔ why moisture✔ bleaching powder✔ uses✔ safety

Extended activity 2 · Uses of oxygen, nitrogen and hydrogen in daily life

2. നിത്യജീവിതത്തിൽ ഓക്സിജൻ, നൈട്രജൻ, ഹൈഡ്രജൻ എന്നിവയുടെ ഉപയോഗങ്ങൾ രേഖപ്പെടുത്തിയ പട്ടിക തയ്യാറാക്കുക. Prepare a table showing the uses of oxygen, nitrogen and hydrogen in daily life.

📋 A sample table – filter it, print it, then add your own rows

Gas	Use	Where we see it	Property behind the use
oxygen	Breathing; artificial respiration	Hospital oxygen cylinders; carbogen (O₂ 95 % + CO₂ 5 %)	needed by living things (“life gas” പ്രാണവായു)
oxygen	Burning fuels	LPG stove, firewood, vehicles	supporter of combustion
oxygen	Welding and cutting metals	Oxy-acetylene flame in workshops	very hot flame with pure oxygen
oxygen	Oxidiser in rocket fuels	Liquid oxygen in rockets	helps the fuel burn where there is no air
nitrogen	Making ammonia and nitrogenous fertilisers	Fertiliser factories (urea, ammonium salts)	source of the element nitrogen
nitrogen	Filling chip and snack packets	Puffed packets in shops	inert – keeps oxygen away so food does not spoil
nitrogen	Filling vehicle tyres	Tyre shops (“nitrogen air”)	inert under ordinary conditions
nitrogen	Liquid nitrogen as a coolant	Storing blood, cells and vaccines in labs	very cold liquid ശീതീകാരി
hydrogen	Making ammonia and methanol	Fertiliser and chemical factories	combines with N₂ / CO
hydrogen	Making saturated oils (vanaspati)	Vanaspati in bakeries and sweet shops	adds to vegetable oils പൂരിത എണ്ണകൾ
hydrogen	Fuel	Rockets (liquid hydrogen); hydrogen buses being tested go further	highest calorific value, forms only water
hydrogen	Getting metals from their oxides	Metallurgy	reducing agent നിരോക്സീകാരി

Festival balloons rise because hydrogen is lighter than air, but hydrogen balloons can catch fire; helium, which does not burn, is the safer choice.

Extended activity 3 · Visit to a fertiliser factory

3. ഏതെങ്കിലും ഒരു രാസവള നിർമ്മാണശാല സന്ദർശിച്ച് പഠനറിപ്പോർട്ട് തയ്യാറാക്കി അവതരിപ്പിക്കുക. Visit a fertiliser factory and prepare and present a study report.

🏭 A Kerala example

The Fertilisers and Chemicals Travancore Ltd (FACT) at Udyogamandal, near Eloor in Kochi, is one of India's oldest fertiliser factories. A school visit has to be arranged by your teacher with the company's permission. If a visit is not possible, interview a Krishi Bhavan officer or study the fertiliser bags sold in a shop, and use the same report template.

🔗 What a nitrogen-fertiliser factory does go further

N₂ + 3H₂ → 2NH₃ (in a factory this needs high pressure, high temperature and a catalyst). Hydrogen and nitrogen are both used for ammonia, as your textbook says.

📝 Field visit report – template

Title: A visit to ______________________ Date: ________ Class/Group: ________

1. Aim

2. About the factory

Location, year started, raw materials, number of units.

3. Products we saw / learned about

Product (fertiliser)	Nutrient(s) it gives	Raw materials	Crop it suits

4. Questions to ask the guide

Where do the nitrogen and the hydrogen for making ammonia come from?
Which fertilisers are made here, and what do the numbers on the bag (N : P : K) mean?
How is the waste water and gas treated before it leaves the factory?
What safety equipment do workers use, and what do they do if a gas leaks?
How does the factory advise farmers on using the right amount of fertiliser?

5. Safety and environment measures we noticed

6. Conclusion – what I learned

⚠ At a factory: stay with your group and teacher, wear the helmet or mask you are given, keep to the marked walkways, touch nothing, and never enter areas marked “Danger” or “Authorised persons only”. Ammonia has a choking smell – move away and tell an adult if you smell gas.

🔑 The ideas that answered everything on this page

Hydrogen: Zn + dilute HCl; burning splinter → pop; highest calorific value (143 kJ/g) but burns explosively and is hard to store. Oxygen: from KMnO₄; glowing splinter bursts into flame. Carbon: diamond (4 bonds, no free electrons, non-conductor) vs graphite (3 bonds, free electrons, conductor); CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂, lime water turns milky. Nitrogen: plant growth, tyres. Chlorine: KMnO₄ + conc. HCl; water removes HCl, conc. H₂SO₄ removes moisture; bleaches only when moist (HOCl → HCl + [O]); chloride test with AgNO₃ then NH₄OH.

🧭 Next

See non-metals at work in daily life: Applications & Explore Online ▶